Afforestation as a mitigation strategy: countering climate-induced risk of forest carbon sink in China.

Background: China has made substantial efforts in afforestation since the 1970s, significantly contributing to the country's forest carbon sink. However, the future carbon sink dynamics remain uncertain due to anticipated changes in forest age structure, climate conditions, and atmospheric CO₂ concentrations. Moreover, the extent to which afforestation can enhance future carbon sequestration has not been fully quantified. This study focuses specifically on China and integrates forest growth models with Maximum Entropy (MaxEnt) models to project future carbon dynamics based on shifts in forest habitat suitability. A nature scenario is applied to evaluate potential climate-induced risks to forest carbon sequestration, while an afforestation scenario is used to assess the additional contribution from planned afforestation efforts.

Results: The baseline aboveground biomass (AGB) of China's forests in 2020 is estimated at 11.59 ± 4.06 PgC. Under the nature scenario and assuming no future disturbances, the total AGB is projected to increase by 5.20-5.74 PgC by the 2050s and by 6.35-8.11 PgC by the 2070s, while carbon sequestration rates are expected to decline from 146.03 to 165.03 TgC/yr to approximately 122.98-137.80 TgC/yr. Between 11.79 and 39.60% of forests are at risk of land loss and compositional shifts in the 2070s, with the situation exacerbated under the SSP585 scenario. To mitigate climate-induced risks, the afforestation scenario proposes an additional 117.90-129.32 Mha of suitable forest area by the 2070s. Newly planted forests are projected to contribute approximately 37.42-65.60% of the carbon sequestration achieved by existing forests during the same period.

Conclusions: Climate change is projected to cause significant forest loss and compositional changes across China. Although total forest carbon storage is expected to increase, the overall rate of carbon sequestration will likely decline. Afforestation emerges as a key strategy to enhance future forest carbon sinks. This study provides a spatially explicit assessment of carbon sequestration potential through afforestation and offers science-based guidance for the design of targeted forest policies in China.